In the metal cutting process, effective chip control is the linchpin of machining stability, surface quality, tool life, and operator safety. For carbide inserts, the design of the chipbreaker (or chip groove geometry) is the decisive factor in determining chip formation and evacuation.
However, in practical applications, many users overlook the suitability of the chipbreaker, focusing solely on the insert grade or coating. This oversight often leads to frequent issues such as bird-nesting (chip entanglement), workpiece scratching, and even edge chipping.
This article provides a systematic guide to selecting the right chipbreaker for carbide inserts based on three critical dimensions: workpiece material, cutting parameters, and machining type.
1. Selection by Workpiece Material
Different materials possess vastly different plasticity, hardness, and thermal conductivity, imposing unique demands on the chipbreaker.
▶High Plasticity Materials (e.g., Low Carbon Steel, Stainless Steel):
These materials tend to produce long, continuous, stringy chips.
•Solution: Select deep and narrow chipbreakers combined with a large rake angle or negative land. This design forces the chip to curl and shear, ensuring effective breaking.
•Example: When machining 304 Stainless Steel, we recommend inserts with "M" or "W" type strong chipbreaker geometries to manage the tough chips.
▶Brittle or Difficult-to-Cut Materials (e.g., Cast Iron, Superalloys):
Cast iron chips naturally break into small fragments, while superalloys are prone to sticking.
•Solution: Use shallow and wide open-style chipbreakers. This design reduces the contact area between the chip and the rake face, minimizing cutting heat and the risk of adhesion (sticking), while ensuring smooth evacuation.
▶Soft Materials (e.g., Aluminum, Copper):
These chips are soft and highly prone to sticking, leading to Built-Up Edge (BUE).
•Solution: Choose polished, sharp, and shallow groove designs with low cutting resistance. This prevents the chips from curling excessively and sticking to the cutting edge.
2. Adjusting for Cutting Parameters and Process Stages
The performance of a chipbreaker is heavily dependent on the cutting data (Feed, Speed, Depth of Cut).
Roughing Operations:
Characterized by a large depth of cut and high feed rates, producing thick and heavy chips.
•Recommendation: Use strong chipbreaker geometries (deep grooves + strong edges). This ensures that large volumes of chips are broken quickly and evacuated to prevent clogging.
Finishing Operations:
Produces thin, wispy chips. Excessive chip-breaking force here can increase cutting pressure.
•Recommendation: Use light or micro-chipbreaker geometries. This maintains cutting stability and ensures a high-quality surface finish.
Technical Warning: If the feed rate is too low (e.g., < 0.1 mm/rev), even strong chipbreakers may fail to break the chip effectively. Instead, it may cause rubbing and aggravate work hardening. Therefore, the chipbreaker must always be designed in synergy with reasonable cutting parameters.
3. Matching Geometry to Machining Type
The operational environment also dictates the optimal chipbreaker design.
External Turning:
Gravity assists in chip removal.
•Choice: General-purpose chipbreakers are usually sufficient.
Internal Turning (Boring):
Chip evacuation space is strictly limited inside the bore.
•Choice: You must use geometries designed for short chips and strong breaking, ideally used in conjunction with high-pressure coolant to flush chips out.
Profiling or Interrupted Cutting:
The tool faces varying forces and impacts.
•Choice: Prioritize chipbreakers with reinforced edges (featuring a T-land or Chamfer). This improves impact resistance and prevents edge chipping during interrupted cuts.
Conclusion
The chipbreaker, though small, is the "invisible engine" that drives the efficiency of a carbide insert. Only by precisely matching the chipbreaker type to the material characteristics, process stage, and machining conditions can you truly achieve clean chip breaking, fast evacuation, and stable cutting.
We advise users not to rely solely on ISO grade numbers. Always consult the chipbreaker application charts provided by your tool manufacturer to implement the "One Condition, One Geometry" strategy. This approach is the key to maximizing both tool performance and economic benefits.
